WASHINGTON – Democratic hopeful Lizzie Pannill Fletcher has laid down a marker in one of the most closely watched U.S. House races in the country, raising more than $1 million in the past three months in her quest to unseat GOP incumbent John Culberson in Houston's 7th Congressional District.

Culberson, who was outraised by Fletcher and other Democratic primary candidates earlier in the race, had yet to release his fundraising numbers Friday for the second quarter of 2018, which ended June 30.

Culberson, targeted by Democrats in his upscale district in west Houston and Harris County, raised $549,078 for his re-election campaign in the first three months of 2018, the largest cash haul of his nine-term career in Congress.

At that point, Culberson had reported a total of nearly $1.5 million in the current election cycle, more than the $1.2 million raised as of March 31 by Fletcher, a Houston attorney.

Recovering from a slow start that alarmed Republicans in Washington, Culberson also retained a substantial cash advantage, with $920,000 in the bank at the beginning of April, compared with $409,000 for Fletcher.

After Fletcher's latest fundraising push, she is reporting $800,000 in a "replenished war chest" after emerging on top in a crowded Democratic primary and run-off election.

The 7th Congressional District race is considered one of the pivotal contests in the battle for control of Congress. Long a Republican district, it narrowly went to Hillary Clinton in the 2016 presidential election, giving Democrats hopes for the 2018 midterm elections.

Culberson had been under pressure from Republicans in Washington to be prepared for a strong challenge in what could be a "surge" year for Democrats angry about the election of President Donald Trump.